Geyser’s trial was scheduled for later in October. But a deal with the Waukesha County District Attorney’s Office prompted her to change an original plea to guilty and Judge Michael Bohren to find her not responsible for her actions due to mental disease or defect, before committing her to continue treatment in a mental hospital, according to CNN. Prosecutors asked Judge Bohren to commit her to 40 years. Doctors at the state Department of Health Service are set to evaluate Geyser by November 13th and recommend to the court how long she should remain committed to a hospital. (Geyser’s attorney did not respond to request for comment.)

In August, her co-defendant, Anissa Weier, pleaded guilty to attempted second-degree homicide. A jury sided with her arguments and found her not responsible for her actions because she was mentally ill, and she was sentenced to three years in a state mental hospital. Last week, after Geyser’s plea hearing, the Leutner family released a statement: “Though we do not believe that an institution is where these attempted murderers belong, the current legal system does not favor victims in this situation.” They added: “With this closure, our daughter is a heroic survivor – and no longer a victim.”

Geyser and Weier, now 15, were just 12 when they were charged as adults after telling authorities that they tried killing their friend Payton “Bella” Leutner, then 12, in order to become “proxies,” or servants, to Slender Man, so that the Jack Skellington-esque Internet meme would not kill them or their families.

It was three years ago last May, the day after Geyser hosted a birthday party, when the girls played hide-and-seek in a forested area near Interstate 94. In Geyser’s retelling of accounts to Judge Bohren: “Anissa said that she couldn’t do it and that I had to,” according to CBS. Geyser “tackled” and stabbed Leutner 19 times with a kitchen knife, before “Anissa told [Leutner] to lie down so she wouldn’t lose blood so quickly, and told her to be quiet, and we left.” Geyser and Weier began walking their planned 300-mile trek to Slender Man’s mansion in Nicolet National Forest. But Leutner eventually crawled out of the forest, where a bicyclist found her and called 911. She survived surgery at a nearby hospital.

Related

This week, Irene Taylor Brodsky, who documented the case in the HBO documentary, Beware the Slenderman, tells Rolling Stone that “the judge gave them no breaks and was punishing them to the fullest extent of the law. He was not allowing their age to be a mitigating factor and that was incredibly difficult for me as a human being to witness. They’re children.” Brodsky adds that the recent plea deal and jury decision show that “the American people can understand that there’s a lot of mitigating nuance here.”

At this time of the attack, HBO and Brodsky were brainstorming ideas on the Internet’s effects on pre-adolescent brains. As it unraveled, producers emailed an article from The New York Times on the Slender Man to Brodsky, who then found herself in Waukesha County, attending the first court appearances and meeting with both the Geyser and Weier families (the Leutner family declined to participate in interviews for the documentary). Today, when Rolling Stone asks how her impressions of the overall case or girls have changed since then, Brodsky answers, “What I came to discover in the course of making the film, I think the jury in Anissa’s case came to discover: These girls were losing their minds in the narrative that was Slender Man. You can’t say Slender Man made them crazy, but most kids don’t watch Slender Man and go out and kill somebody. You have to look at this through the prism of their mental illness.” Brodsky says the girls were involved in “a folie a deux, a delusion shared by two personalities” that allowed them to fall deep into the psychological grip of Slender Man.

Neurodevelopmental psychologist Abigail A. Baird, a psychology professor at Vassar College who was interviewed in Brodsky’s film, tells Rolling Stone that Geyser “was diagnosed with unspecified psychosis and schizophrenia” – mostly non-violent unless of a paranoid nature – and Weier was diagnosed with “a shared delusional disorder.” Geyser’s defense attorneys say that she believes she could communicate telepathically with Slender Man and see characters from Harry Potter and Teenage Mutant Ninja Turtles. Baird says Weier’s YouTube search history includes “psychopath tests,” a snake killing a mouse, a bunny eating raspberries. “Morgan continues to believe in Vulcan Mind control and the videos show you Anissa is a patch work, who was vulnerable to something violent,” says Baird, who stresses that her opinion is based on speculation.

As Brodsky sees it, the girls had a dangerous concoction of mental illness, obsession and isolation at a young age. “A perfect confluence of circumstances,” Brodsky says.

Baird agrees, and explains the susceptibility of age: “The girls were prepubescent at the time of the attack, which added another layer of immaturity. They were just old enough to feel like they had to have friends, but they were young enough to believe in Santa Claus. I can’t get my mind around trying 12 year olds as adults. Would you honestly want these girls on a jury if you were in trouble? Because that’s what that means. They’d give you life because they don’t like your shirt.”

Prosecutors and Judge Bohren have voiced concerns over how the girls apparently premeditated the attack. But Baird sees the act of adolescent premeditation much differently, saying, “kids at this age make plans to go to outer space.” But Baird draws attention to their isolation: “They didn’t have a bigger group of friends, where someone could have said, ‘Slender Man doesn’t exist.” Baird also focuses on obsession: “This is why pop musicians get so popular. If one girl likes them, all have to like them. But it’s usually regulated fluff and not harmful or violent. In Anissa and Morgan’s case, it was something antisocial.”

Of course, Slender Man alone did not force the girls to wield a knife and try and kill their friend. “People try to say that movies and music make people do violent things, but it doesn’t work that way,” Baird says. “People who are prone to violent acts feel validated by violent music and movies, so they will look for validation in those worlds. These girls were drawn to Slender Man.”

From the Internet boogeyman’s ties to bullying, to Morgan Geyser’s dad’s tearful interview, the documentary sheds new light on a terrifying story. Watch here.